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MicrogridA new hub in energy

infrastructure

Mohammad Shahidehpour - Illinois Institute of Technology

Outline

• Smart Grid Technology – Electricity Infrastructure– What is Smart Grid

• Microgrids (IIT Perfect Power Project)– Components– Hierarchical Control, Islanding and Synchronization– Optimal Operation of Microgrid– Reliability Evaluation

• Perfect Power System – Robert W. Galvin Center at IIT

3

4

Restructuring

TRANSCO

GENCO

DISCO

Power System

GENCO GENCO

GENCO

GENCO

GENCO

Tie-Lines

Tie-Lines

DISCO

DISCO

C1 C2 C3 C4 C5 C6

Electricity Infrastructure

• Supply Adequacy and Economics: Applications of renewable energy, storagetechnologies for enhancing the security, coordination of renewable and storagesupplies, carbon footprints

• Transmission Expansion and Security: Expansion planning of transmission facilities,coordination of energy infrastructures, superconductors, HVDC, physical and cybersecurity, wide area measurements, PMUs

• Smart Grid: Energy efficiency, price response, peak load reduction, distributionautomation, new building technologies, smart metering, sensors, communication andcontrol techniques

What is Smart Grid? • Smart grid is a response to economic, security, and environmental

mandates placed on energy supply and delivery• Smart grid provides access points that can be identified, much like

computer devices, with an IP address on the internet• Smart grid uses the internet protocol to shuttle information back and

forth between the utility and customers• With two-way communications between consumers and suppliers, both

parties can get far more control over the grid consumption, and physicaland cyber security

Demand in MW

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Time 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

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4

10

6

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16

14

12

2

Price [¢/KWh]February 24, 2000

Cost-based Price

Demand

Demand in a Vertically integrated Power Market

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Demand in MW

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5

3

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8

7

6

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Time

18

4

10

6

8

16

14

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2

Price [¢/KWh]

Customer Demand

Market-based Price

February 24, 2000

Response of a Demand to Price Signals

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Introduction to Microgrids• Microgrid is a system with at least one distributed energy

resource (DER) and one demand which can be islandedfrom the main power distribution system (US DOE).

• Microgrids would address the emergence of a largenumber of DERs in distribution systems and to ensuresecure and optimal operations of potentially islandedpower grids.

• Microgrids generate, distribute, and regulate the flow ofelectricity to local customers, representing a modernsmall-scale power system with a high degree of flexibilityand efficiency in both supply and demand sectors.

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Operation and Control of an Operational Microgrid for Service Restoration

• The short-term reliability algorithm devised at themicrogrid master controller would consider seamlessislanding and resynchronization and apply emergencydemand response and self-healing in case of majoroutages on either sides of the PCC.

• The economic operation would address the optimalgeneration scheduling of DER units in grid-connectedand island modes and would apply economic demandresponse for minimizing the operation cost.

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10

Footprint of Hurricane Sandy

Service Restoration Using Microgrids• Microgrid can assist distribution system service restoration

processes by providing one or more of the following services:

– Islanding from the grid for the local supply of microgridloads and reducing the supply provided by the utility grid.

– Coordinated reduction in microgrid loads by rendering anemergency demand response and curtailing non-criticalloads that would minimize the impact of outage on theleast number of customers.

– Increasing the microgrid generation for supplying localloads, and if possible, providing the microgrid surplusgeneration to the utility grid.

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Distribution System Service Restoration Using Microgrids

• A distribution system may consists of a multi-microgrid system comprising severalmicrogrids each equipped with DER units connected through power electronicinterfaces and storage devices to provide power balances to a wider area duringblackouts.

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Goals of the DOE RDSI Project

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• 50% peak demand reduction

• 20% permanent demand reduction

• Demonstrate the value of Perfect Power

• Cost avoidance and savings in outage costs

• Deferral of planned substations

• New products and commercialization

• Replicable to larger cities

• Promotion of energy efficiency in cleaner cities

• Funded by the U.S. Department of Energy

• Located at Illinois Institute of Technology (IIT)

• Involves the entire campus

• Partners: IIT, Exelon, S&C, Schweitzer, Siemens, Schneider, Eaton, GE, Invenergy, Intelligent Generation, ZBB, Viryd, I-GO, Smart Signal, Catch The wind, Veriown, Keri

Perfect Power at Illinois Institute of Technology

“The perfect power system will ensure absolute and universal availability of energy in the quantity and quality necessary to meet every consumer’s needs. It is a system that never fails the consumer.” Bob Galvin

15

16

North

substation

South

substation4.16kV

12.47kV

4.16kV

PCC

Utility grid

Vis

ta1

E

Battery

Gas-turbine

Synchronous

Generators

Lo

op

1

Lo

op

3

Lo

op

7

PV

Lo

op

2

S

S

S

PV

SPV

PV

SEng.1

Vis

ta1

D

Wind

Vis

ta1

B

LS

Stuart

VanderCook

Machinery

CTA1

CTA2

Vis

ta1

A

Vista1C

High Reliability Distribution System (HRDS)• Implementation of microgrid loops is made possible by the use of automatic switches in

HRDS.• HRDS switches can sense the cable faults and isolate the faulted section with no impact on

other sections in a microgrid.

• No HRDS– Fault takes 30 cycles to clear.– The system is radial. Once the breaker opens, all the loads downstream will be

disconnected.• HRDS

– Fault takes 6 cycles to clear.– The system is loop. Once the breakers open, only the faulted cable is isolated.

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HRDS Switches at IIT Microgrid

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Vista Switch 1 Vista Switch 2

MV Breaker

(a)

(b)

Generator

Motor 1

Motor 1

Motor 2

Motor 2

Generator

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

1.05

0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0

Spe

ed (

p.u)

Time (Sec)

Without HRDS

With HRDS

Power Plant Control at IIT Microgrid

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( )rated Sync.

Gen.Gas

Turbine

2nd

MT

Exciter

V

refP

refQ

Q

2ndV

ratedV

Tertiary

Control

P-ω

Primary

P-ω

Secondary

P

Q-V

Primary

Q-V

Secondary

Renewables at IIT Microgrid

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Charging Station, Solar Canopy, Flow Battery

Operation and Control of an Operational Microgrid for Service Restoration

• The three control levels in microgrids include:– Primary control which is based on droop characteristics of

DER units for sharing the microgrid load.

– Secondary control performs corrective action to mitigate frequency and voltage errors introduced by droop control.

– Tertiary control manages the flow between the microgrid and the utility grid and provides the optimal scheduling of DER units and demands in islanded and grid-connected operation of microgrid. Tertiary control would also provide ancillary services to the utility grid including voltage and frequency regulation and restoration services.

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Operation and Control of an Operational Microgrid for Service Restoration

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Hierarchical Control of Microgrid

• Primary & Secondary Control

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2 3 4 6

60Hz

59.9Hz

f (Hz)

P (MW)

Droop1 (0.1Hz/MW)

Droop2 (0.05Hz/MW)

20 30 33 60

V0

4.00

V (kV)

Q (kVar)

Droop2

(1.5V/kVar)

Droop1

(0.7V/kVar)3.98

Primary controlSecondary

control

/f V

/P Q

rated

No change

in dispatch

A

B

C

Tertiary Control -- Microgrid Master Controller

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Master

Controller

Solar (PV)Wind DAS

Thermal Generation

Generation Control

System

Building Control System

Sub-Building

Zigbee Control

System

Distribution System Control

Battery StorageCharging Station

Storage Control

System

Master Controller Formulation

• Master controller is responsible for the economic operation of themicrogrid based on signals received from HRDS switches.

• It monitors the status of HRDS switches using the SCADA system.

• It implements a three level hierarchical control (master, building,sub-building)

• It forecasts the real-time price of electricity and optimizes thehourly stochastic unit commitment/dispatch of local generation.

• Forecast errors of day-ahead load and wind speed and randomoutages of microgrid DG/distribution lines are considered.

• Monte Carlo representation of outages is applied and the LatinHypercube Sampling (LHS) technique is used to develop a largenumber of scenarios with equal probabilities.

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Master Controller Formulation

27

, , , ,

, ,, , ,

( )

.( )

s s s sc i i t i t i t

t is

s D s d sst g t b t b t

t b

F P SU SD

Min pP VOLL P P

, , , , s s s s

i t g t k t D ti k

P P P P

, , , 1( ) s s si t i i t i tSU CS I I

, , 1 ,( ) s s si t i i t i tSD CD I I

min max, , , , , s s s s s

i i t i t i t i i t i tP UX I P P UX I

min max, , , s s s

g g t g t g g tP UX P P UX

Problem Formulation

28

,, , , ,,

, , , , ,

net s s sdc k t k c k tk t

s s sk t dc k t c k t

E P P

P P P

, , , , 1 s sdc k t c k tI I

min max, , , , , , , ,

min max, , , , , , , ,

s s sc k t c k c k t c k t c k

s s sdc k t dc k dc k t dc k t dc k

I P P I P

I P P I P

min max, , , , , , , , ,( ) ( ) s s s s

k dc k t c k t k t k dc k t c k tQ I I Q Q I I

,, , 1 ,

min max,

,0 ,

s s net sk t k t k t

sk k t k

k k NT

E E E

E E E

E E

Problem Formulation

29

,,, , , ,,

i g k dj j j j

inj ss s s d si t g t k t j tD t

i D g D k D d D

P P P P P

,,, , , ,,

i g k dj j j j

inj ss s s d si t g t k t j tD t

i D g D k D d D

Q Q Q Q Q

, ,, ,, ,, , ,

, , , 2 2 2 2, , , ,

t s t so j o jo j o jt s t s t s

o j o j o j

o j o j o j o j

r U x Uy g jb j

r x r x

Problem Formulation

30

, 2 ,

, , ,

, ,

, , , , , , , ,

( )

( )

[ sin( ) cos( )]

inj s s t s

j t j t j i

NBs s t s s s t s s s

j t o t j o j t o t j o j t o t

o j o

Q V B

V V G B

, , , ,

, , , , , , , , ,

( )

(2 1) ( 1) ( )NB

inj s s t s t s s s t s s s

j t j t j j j o j t o t j o j t o t

o j o

Q V B B V V G

, 2 ,

, , ,

, ,

, , , , , , , ,

( )

( )

[ cos( ) sin( )]

inj s s t s

j t j t j j

NBs s t s s s t s s s

j t o t j o j t o t j o j t o t

o j o

P V G

V V G B

, , , ,

, , , , , , , , ,

( )

(2 1) ( 1) ( )NB

inj s s t s t s s s t s s s

j t j t j j j o j t o t j o j t o t

o j o

P V G G V V B

Problem Formulation

31

, 2 , 2 , 2

, , ,( ) ( ) ( )t s t s t s

j o j o j oQL PL SL

, max

, ,

t s

j o j oSL SL

, 2 ,

, , ,

, ,

, , , , , , , ,

( )

[ cos( ) sin( )]

t s s t s

j o j t j j

s s t s s s t s s s

j t o t j o j t o t j o j t o t

PL V G

V V G B

, , , , , , ,

, , ,( ) ( )t s t s t s t s t s t s t s

j o j o j o j o j oPL G V V B

, 2 ,

, , ,

, ,

, , , , , , , ,

( )

[ sin( ) cos( )]

t s s t s

j o j t j j

s s t s s s t s s s

j t o t j o j t o t j o j t o t

QL V B

V V G B

, , , , , , ,

, , ,( ) ( )t s t s t s t s t s t s t s

j o j o o j j o j oQL B V V G

, , , ,

, , , ,

t s t s t s t s

j o j o j o j oSL PL QL

Optimal Operation of MicrogridPHASE V (Peak Load Reduction)

0

5

10

15

20

25

30

-1000

1000

3000

5000

7000

9000

11000

13000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Pow

er

(kW

)

Time (Hour)

Utility Grid Supply

Total Demand

Utility Grid Supply With Building Controllers

Price of Electricity

Ele

ctr

icit

yP

rice (

cents

/kW

h)

Case No HRDS HRDS HRDS + Storage

Exp. SAIDI 1.22 0.18 0.04

Exp. SAIFI 3.29 0.59 0.37

Exp. CAIDI 1.73 0.36 0.04

Exp. CAIFI 2.69 0.68 0.29

Exp. Operation Cost 224,073 146,899 120,038

Exp. Energy not Supplied 1,216.21 251.07 175.10

LOLE 13.153 2.360 1.467

Mohammad Shahidehpour PhD

• ms@iit.edu

• Bodine Chair Professor / Director

• Galvin Center for Electricity InnovationIllinois Institute of Technology, LLC

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